| Abstrakt: |
The aim of this research is to study the structural behavior of six self-compacting concrete box beam and evaluate the strengthening techniques and their impact on the structural behavior of the box beam under the effect of pure torsion. The strengthening techniques used in this study are: (steel plate, steel bracing, steel fiber, carbon fiber reinforced polymer (sheet and bar). All beam specimens have the same dimensions of (2200x350x350mm) for length; width and depth respectively, and (70mm) wall thickness, were casted and examined under pure torsion up to failure. The experimental work included two groups of beams in addition to one control beam. The first group comprised two beams with an internal Strengthening techniques such as (steel bracing and steel fiber (1%)), while the second group contained three beams with an external strengthening techniques by using (steel plate and carbon fiber reinforced polymer (sheet and bar)). The crack pattern, modes of failure, longitudinal deflection, and also measured and discussed the applied torque-angle of twist relationship at the end and mid span. The results of the experiment showed a significant increase in the ultimate torsional capacity strength by 37.7 %, 41.2 %, 72.9 %, 82.4 %, and 84.7 % for beam specimens strengthened by CFRP-bar, CFRP-sheet, steel fiber, steel plate and steel bracing, respectively, in comparison to the reference specimen. In addition, the adopted strengthening techniques have shown good efficiency in increasing the section tor-sional capacity in comparison to the reference beam. [ABSTRACT FROM AUTHOR] |
